Telephone system.



H. P. CLAUSEN. TELEPHONE SYSTEM.

APPLIOATION FILED 33.21, 1902.

Patented Aug. 6, 1912.

4 SHEETS-SHEET 1.

H. P. GLAUSEN.

TELEPHONE SYSTEM.

APPLIGATIOH FILED IEB.21, 1902.

Patented Aug. 6, 1912.

R Q mm couuuu mun-mum co. wasnmc'rou. n. r.

H. P. GLAUSEN.

TELEPHONE SYSTEM.

APPLICATION FILED 123.21, 1902.

1,034,875. Patented Aug. 6, 1912.

4 SHEETS-*SHEET 3 H. P. CLAUSEN. TELEPHONE SYSTEM.

APPLICATION FILED 11:3.21, 1902.

Patented Aug. 6, 1912.

4 SHEETS SHEET 4- lid 226556,: fi

COLUMBIA PLANOURAPH 410., WASHINGTON. n. c.

UNITED STATES PATENT OFFICE.

HENRY P. CLAUSEN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS,TO STROMBERGr-CARLSON TELEPHONE MANUFACTURING COMPANY, OF ROCHESTER, NEWYORK, A CORPORATION OF NEW YORK. 4

TELEPHONE SYSTEM.

T 0 all whom it may concern:

, Be it known that I, HENRY P. CLAUsEN, a citizen of the United States,and residing at Chicago, in the county of Cook and State of Illinois,have invented. certain new and useful Improvements in Telephone Systems,of which the following is a specification.

My invent-ion relates to telephone systems in general, but moreparticularly to systems in which complete metallic circuits are employedbetween the substations and the central exchange, and in which thecurrent for operating certain signaling devices is supplied from acommon battery located at the central station. In telephone systems ofthis character, the substations are connected with the central stationby means of complete metallic circuits, rather than by groundedcircuits, and the current for operating the various signals is suppliedentirely from the central exchange. Signals, usually bells, are providedat the substations, whereby the central operator may call up thesubscribers, and other signals, known as line signals, are provided atthe central station, whereby the subscribers may call up the centraloperator. In addition to these, supervisory signals are also provided,whereby the central operator may know when the subscribers have hung uptheir receivers. Both the said line and supervisory signals usuallyconsist of small incandescent lamps which are arranged on the switclrboard in front of the central operator. The circuits for these lamps arecontrolled by relays, arranged to be either energized or deenergized bythe manipulation of the hook switches at the substations. The operatoris usually provided with a cord circuit, with which the supervisorysignals are associated, and which is provided with a pair of plugsadapted to be inserted in the jacks connected with the subscriberslines. In this way, a subscriber may close a line circuit by removing areceiver from the hook at the substation, and the closed line circuitwill operate the relay controlling the circuit of the line signal. Thedisplaying of the line signal in this manner attracts the attention ofthe central operator, and the latter then inserts the answering plug ofthe cord-cir- Specification of Letters Patent.

Application filed February 21, 1902.

Patented Aug. 6,1912.

Serial No. 96,009.

cuit in the jack allotted to the calling subscriber. After learning thenumber of the substation desired, the operator then inserts the other orcalling plug of the cordcircuit in the jack of the line allotted to thecalled-for subscriber.

It is usually the practice to provide certain arrangements whereby theinsertion of the plug in the jack of the calling subscriber will operateto extinguish the line signal. The supervisory signals are automaticallyoperated and displayed when the subscribers hang up the receivers, andthe central operator then withdraws the plugs of the cordcircuit fromthe two jacks. Ordinarily, the current, both for operating the relaysand lighting the signal-lamps, and also for the transmitters at thesubstations, is supplied from a common battery located at the centralexchange. It is desirable, however, at times to connect up a centralexchange of this character with substations having local batteries-thatis to say, with substations at which batteries are located for supplyingcurrent to the transmitters. In such case, the system is operated partlyby current from the battery at the central exchange and partly bycurrent from the batteries at the substations. Prior to my invention,more or less difliculty has been encountered in thus connecting up localbattery substation apparatus with central exchange apparatus operatingon the central energy principle.

It is, therefore, one of the principal objects of my invention toprovide an improved circuit arrangement, whereby local batterysubstation apparatus may be connected up and made to operatesatisfactorily with a central energy exchange. A special object is toprovide an improved circuit arrangement, whereby connection of thischaracter may be made without causing battery current to flow throughthe receivers at the substations.

It is also an object to provide certain details and features ofimprovement tending to increase the general efficiency and to render atelephone system of this character more serviceable and satisfactory inuse.

To the foregoing and other useful ends,

my invention consists in matters hereinafter set forth and claimed.

In the accompanying drawings, Figure 1 is a diagram illustrating atelephone system involving the principles of my inven tion, and in whichsubstations having local batteries are connected up with a centralenergy exchange. Fig. 2 is a view similar to Fig. 1, but showing onlyone substation having a local battery, and the other having atransmitter adapted to be supplied with current from the common batteryat the central exchange. Fig. 3 is a simplified diagram showing themanner of supplying current to the lines with the circuit arrangement ofthe substation apparatus shown in Fig. 2. Fig. 4 is a diagram similar toFig. 1, with the exception that in this view a condenser is shown ineach strand of the cord circuit, and two coils are shown in thecontrolling relay for operating the su pervisory signals. Fig. 5 is adiagram similar to Fig. 4:, but showing the central exchange connectedwith substations of different character. Fig. 6 is a simplified diagramof the circuit arrangement shown in Fig. 5.

It will be readily understood that the instruments involved in thesubscribers or substation equipments at the different substations shownmay be of any suitable, known or approved character consistent withtheir use in connection with either common battery or local batterytransmission. Furthermore, it will be readily understood that theswitchboard equipment at the central station can be of the usual type,generally speaking, there being springjacks, as illustrated, andhereinafter more fully described, at which the subscribers linesterminate, and also operators cords or cord-circuits provided with plugsadapted for insertion in these spring-jacks for the purpose ofestablishing connection between any two subscribers lines. Also, it isobvious that the various relays, impedance coils and lamp signals can beof any suitable known or approved form or construction. The nature andconstruction of the telephone system and the purpose and functions ofthe various instruments and devices will, however, be best understood bydescribing the operation of the system as a whole.

Therefore, as illustrated and described, and referring to Figs. 1, 2 and3, the operation of the system is as follows. As suming that thesubscriber at substation S desires connection with the subscriber atsubstation S, as shown in Fig. 1, the subscriber at substation S firstremoves the receiver X from the hook-switch, and thereby completes aline circuit from the battery B, through conductors 1 and 2, through the1mpedance coil 3, through the line conductor 1,

through the impedance coil 5, through conductor 6 and the secondary 7 ofthe induc tion coil, through the contact-point 8 and the hook switch 9,through the line conductor 10 and the coil 11 of the line relay R,thence through the conductor 12 and the impedance coil 13, and throughthe conductors 14, 15 and 1G to said battery. This, it will be seen,energizes the line relay R and causes the latter to attract itsarmature. In this way, the line relay closes the short local circuitfrom the battery through the conductor 1 and the ground or commonconnections 17 and 18, through the relay armature 19, through thecontact point 20, thence through the lamp 21 and the conductor 22, andthrough conductors 14, 15, and 16 to said battery. A current flowingthrough this local circuit lights the line signal lamp 21, and in thisway the central operator is advised that a call has been sent in fromthe substation S. Acting on this signal, the central operator theninserts the answering plug P of the cord-circuit in the jack J, therebyestablishing another local circuit from the battery B through conductor23, through the coil 24 of supervisory relay R, through the conductor 25and the cord-strand 26, thence through the sleeve contact 27 of the saidplug, through the ring or thimble contact 28 of the jack J, thencethrough the conductor 29 and the impedance coil 3, and through theconductors 2 and l to said battery. This energizes the supervisory relayR and causes the latter to attract its armature. It will also be seenthat the insertion of the answering plug in this manner operates toshunt out the line relay R, by reason of the tip and ring contacts 30and 31 of the plug making contact with the tip and ring contact springs32 and 33 of the jack. The contacts of the plug and jack thus broughtinto contact allow current to pass from the line 10 through the tipspring 32 and the tip contact 30, thence through the cord-strand 3 1,through the coil 35 of the supervisory relay B", through the conductor36 and the plug ring contact 31, and thence through the contact spring33 of the jack, and the conductor 37. The coil of the relay R is oflower resistance than the coil of the relay R, and consequently thesupervisory relay R and its connections constitute a shunt for shuntingout and deenergizing the line relay R.

As stated, the insertion of the plug causes the current to energize thesupervisory relay R, thereby closing the normally open switch-point inthe supervisory lamp circuit, but it will also be seen that at such timethe energization of the relay R operates to open one of the normallyclosed switch-points in the supervisory lamp circuit. Consequently theenergization of the controlling relay R by the insertion of the plugdoes not cause the supervisory lamp L to light. At this point, theoperator communicates with the calling subscriber in any suitablemanner, as, for example, by employing the usual operators talking setand listening key, and after learning the number of the substationdesired, the operator then inserts the calling plug P in the jack J. Itwill be observed that this jack J is connected with the line leading tothe substation C. it will also be observed, however, at this juncture,that the insertion of the calling plug P in the jack J, and theconsequent encrgization of the relay R, has caused the supervisory lampL to light, inasmuch as the superisory relay R is not energized. Thislamp L remains lighted until. the subscriber atsubstation S answers thecall. 'hen the subscriber at S removes the receiver X from thehook-switch, a line circuit is completed from the battery B. through theconductor 38, thence through the impedance coil 39, through the lineconductor 40, through the impedance coil 11, through the conductor 42,through the secondary 43 of the induc tion coil. through contact point 41, through the hoolcswitch 45, thence through the line conductor 46,through the tip spring 47 of the jack J, through the tip contact 48 ofthe plug, thence through conductor 51 and the ring contact 52 of theplug, through the ring contact spring 53 of the jack, through conductors54 and 55, through the impedance coil 56, thence through conductors 14-,15 and 16 to said battery. The battery current flowing through this linecircuit energizes the supervisory relay R inasmuch as the latter is oflower resistance than the line relay R and causes the said supervisoryrelay to attract its armature. This, it will be seen, breaks the localcircuit through which the lamp L is lighted, thereby ad vising thecentral operator that the subscriber at substation S has answered thecall. Also, as the said relay It is of lower resistance than the relay Rthe latter does not become energized by the closing of the line, andconsequently the subscriber at substation S in answering the call doesnot cause the line lamp signal 57 to be displayed. \Vith both receiversremoved from the hook at the two substations, the subscribers areconnected for talking purposes, the talking circuit, it beingunderstood, consisting of the line conductors between the substationsand the central exchange and the talking strands of the cord-circuit.Preferably, a condenser C is located in the strand of the cord-circuit,connecting the tips of the two plugs. In this way, the battery currentprevented r0111 flowing through the said strand, and at the same timethe latter is capable of serving as a conductor for voice currents.

\Vhen the subscriber at substation S hangs up the receiver X, the linecircuit is broken, and the relay R de'e'nergized. This causes thelatters armature to close a short local circuit from the battery throughthe conductor 16, through the armature 58, through the contact-point 59,through the conductor 60, through the conductor 61, through the lamp L,through the contact point 62, through the armature 613, through theground or common connections (3+ and 17, and through the conductor 1 tosaid battery. This lights the supervisory lamp L and advises the centraloperator that the subscriber at substation S is through talking. In asimilar manner, when the subscriber at substation S hangs up thereceiver X, the line circuit of the substation is broken, and thesupervisory relay dei inergized. The latter, in releasing its arma ure,causes the local circuit to be closed from the bat tery B, through theconductor 16, through the armature 58 and the contact-point 59, thencethrough the conductor 60, through the supervisory lamp L, throughcontactpoint 65, through the armature 66, thence through the ground orcommon connections 67 and 17, and through the conductor 1 to saidbattery. The current flowing through this local circuit lights thesupervisory lamp L, indicating, as in the previous case, that thesubscriber at substation S has also hung up the receiver. The centraloperator then withdraws the. plugs, and the system is then in its normalor disconnected condition, as hown in the drawings.

As previously stated, it will be understood that the operators talkingset can be of any suitable form or character, and can be connected withthe cord circuit in the usual and well known manner. In this cminectionit will also be readily understood that the op erator can be providedwith the usual generator for ringing the bells 1 at the substations.These bells are bridged across the lines and arranged in series with thecondensers D. It will be observed that these condensers are three-way incharacter, and that consequently each condenser is also in series withthe associated receiver. impedance coils 5 and 41 are in parallel withthese condensers, and are also preferably in parallel with thereceivers. With this arrangement, the talking circuits include thecondensers, while the battery circuits include the impedance coils 5 and41. In this way. the battery current does not llow through the receiversat the substations.

In Fig. 1 both substations are provided with local batteries Z forsupplying current to the transmitters T. Each transmitter is providedwith a local circuit including a local battery, and also including theprimary of the induction coil and the hookswitch. \Vhen the hookswitches are down, as shown in the drawings, both the line and the localcircuits are open, and the bells are in circuit with the lines throughthe condensers, which latter permit generator ringing current to pass,but Which prevent the passage of battery current. \Vhen the hookswitches are up, the receivers are connected in the lines through thecondensers, which latter also permit the passage of voice currents. Inthis way, the central energy exchange can be connected up with localbattery substations, and connections of this character can be madewithout causing battery current to flow through the substationreceivers. The three-way condensers simplify the arrangement byobviating the necessity of encumbering the subscribers sets with anumber of condensers. It will also be seen that the line and supervisorysignals are operated in a simple and etiicient manner, and that thesystem, although simple and involving comparatively t'ew circuits anddevices, is nevertheless characterized by substantially all of theapproved methods of operation. it will be readily understood that theresistance of the various resistance coils and relays can be adjusted orregulated by those skilled in the art, and in accordance with thecondititms of any particular case.

In Fig. 2, the circuit arrangement is substantially the same as shown inFig. 3, with the exception that the apparatus at substation S' does notinclude a lo a1 battery, and in this case. therefore, the QXClitlllQG isconnected up with a local battery substation, and also with a substationhaving such apparatus as is usually employed in connection with centralenergy systems. Thus it will be seen that with my improved circuitarrangement, a central energy exchange can be connected up with bothlocal battery and common battery substations.

in Figs. 4-. 5. and ti. the substation apparatus substantially the sameas shown in the preceding tigurcs, it being observed that n Fig. l thecentral exchange is connected up with two local battery substations.while in Figs. and ('3 the exchange is connected up with one localbattery station and one common battery station. In said Figs. 4-, 5, andt), it will be seen, however. that the cord-circuit involves a secondcondenser t in addition to the condenser (l of the previous diagrams,and, furthernun'e. that the relay R is provided with two coils insteadof one. The two coils r and 1" of this double-coil relay are interposedbetween the battery and the lower strand of the cordcircuit, one coilbeing connected at one side of the condenser (,l', and the other coil being connected at the other side. Vith this arrangement, the insertion ofthe plug P Will energize the coil 1, While the insertion of the plug Pwill energize the coil r, consequently the insertion of either plug willclose the controlling supervisory relay R, thereby closing the normallyopen switch-point in the supervisory lamp circuits. The insertion ofeither plug, therefore, as is also the case With the arrangement shownin Fig. 1, places the supervisory lamp circuits in readiness to beclosed by the deenergization of the supervisory relays R and R Vith thecircuit arrangementshown, it will be seen that the battery is connecteddirectly to the line, rather than through the medium of the cordcircuit. In Figs. 8 and 6, the relative arrangement of the coils isshown through which the current is supplied to the lines. As stated, thethree-Way condensers not only prevent the flow of battery currentthrough the receivers at the substations, but also prevent thecontinuous operation of the line signals.

hat I claim my invention is- 1. A telephone system comprising asubstation and a. central station and suitable line connection betweenthe same, a line signal at the central station, a source of current atthe central station for operating said line signal. a local battery anda transmitter in a normally open local circuit at the substation, areceiver and a condenser connected in series in the line at thesubstation, a hook-switch for said receiver, a bell connected betweensaid condenser and the contact-point upon which said hook-switchnormally rests, and an impedance coil arranged in parallel with saidreceiver and condenser.

2. A telephone system comprising a subscriber-"s line, a jack connectedwith the line at the central station, a source of current permanentlyconnected with the line, a cordcircuit having a plug adapted forinsertion in said jack, a line lamp signal having a nta-mally open localcircuit including said source oi current supply, a line relay forcontrolling said normally open local circuit, a condenser and a receiverin the line at the substation, a hook-switch for said receiver, a localbattery and a. transmitter included in a normally open local circuit atthe substation, and an impedance coil arranged in parallel with saidreceiver and condenser.

3. In a telephone system, a subscribers line, a transmitter and areceiver at the subscriber's station, a three-way condenser included inthe line circuit and also in a bridge across the line, and a hook-switchfor said receiver adapted to form part of said bridge when the receiveris in place.

4.. In a telephone system, a subscrihers substation, apparatus,comprising a receiver and a transmitter, a hook-switch for saidreceiver, a bell and a three-way condenser, said condenser, bell andhook-switch constituting a bridge across the line, said condenser beingalso connected in series with the receiver, a local battery, aninduction coil having its primary located in a local circuit includingsaid battery and transmitter, the secondary of said induction coil beingin series with the receiver when the latter is off said hook-switch, andan impedance coil arranged in parallel with said receiver and condenser.

5. In a telephone system, a line circuit, a bridge across the linecircuit and a threeway condenser forming part of the line-circuit andalso part of the bridge across the line-circuit, an operators cordcircuit, two supervisory relays, a local circuit, a central station,suitable means and connections whereby one supervisory relay in theoperators cord circuit is energized over said local circuit completedwhen a cord-connection is established to line, and whereby the othersupervisory relay in such cord circuit is energized over the linecircuit opened when the subscriber on the connected line hangs up hisreceiving telephone.

6. In a telephone system, a line circuit, a bridge across the circuithaving a normally closed switchpoint, a three-way condenser forming apart of the line circuit, and also part of said bridge, and an impedancecoil connected in parallel with the condenser, the circuit in which theimpedance coil is located being normally open.

7. In a telephone system, a subscribers line connecting a substationwith a central station, a line relay at the central station, a batteryat the central station permanently connected with the line, acircuit-changing device and an impedance coil at the substation forclosing the line at the latter point and thereby energizing said relay,a condenser arranged in parallel with said impedance coil, and areceiver arranged in series with said condenser and in parallel withsaid impedance coil, the parallel connection in which the impedance coilis located being adapted to permit the passage of battery current whenthe line is closed by the said circuit-changing device, an operatorscord circuit, two supervisory relays, a local circuit, a centralstation, suitable means and connections whereby one supervisory relay inthe operators cord circuit is energized over said local circuitcompleted when a cordconnection is established to line, and whereby theother supervisory relay in such cord circuit is energized over the linecircuit opened when the subscriber on the connected line hangs up hisreceiving telephone.

8. A telephone system comprising a substation and a central station andsuitable line connection between the same, a line relay at the centralstation, a source of current at the central station permanentlyconnected with the line, a circuit-changing device at the substation, abridge having a switchpoint normally closed by said circuit-changingdevice, a condenser located in the line and also forming a part of saidbridge, a bell in said bridge, and an impedance coil arranged inparallel with the condenser and receiver and forming a part of the linecircuit when the latter is closed by said circuitchanging device.

9. A telephone system comprising a pair of subscribers lines, a centralexchange at which said lines terminate, a relay in each line, a centralsource of current supply connected with the lines, a transmitter at oneof said substations adapted and arranged to be supplied with currentfrom said central source of current supply, an induction coil having itsprimary arranged in series with said transmitter, a receiver connectedwith both terminals of the secondary of said induction coil, atransmitter and a local battery included in a normally open circuit atthe other substation, said local battery circuit also including theprimary of an induction coil, a condenser and a receiver connected inseries in the line at the substation having said local battery, and animpedance coil arranged in parallel with said receiver and condenserwhen the line is closed.

10. In a telephone system, a subscribers substation apparatus providedwith a threeway condenser forming inductive talking and ringingconnection in said apparatus, an operators cord circuit, two supervisoryrelays, a local circuit, a central station, suitable means andconnections whereby one supervisory relay in the operators cord circuitis energized over said local circuit completed when a cord-connection isestablished to line, and whereby the other supervisory relay in suchcord circuit is energized over the line circuit opened when thesubscriber on the connected line hangs up his receiving telephone.

11. In a telephone system, the combination of substations and a centralstation and suitable line connection between the same, a twowaycord-circuit, a condenser in one strand of said cord-circuit,supervisory relays connected with the cord strand provided with saidcondenser, supervisory lamps each having a local circuit provided withtwo switchpoints, one normally open and the other normally closed, thenormally closed switchpoints being controlled by said supervisoryrelays, a central source of current supply for operating said lamps andrelays and for supplying current to the lines, a third supervisory relayfor controlling the normally open switch-point in the circuits of saidsupervisory lamps, line lamp signals having normally open circuitsincluding said source of current supply, line relays for controlling thelocal circuits of said line lamps, transmitters and local batteriesincluded in normally open local circuits at the substations, condensersin the lines at the substations, receivers connected in series with saidcondensers, and impedance coils arranged in parallel with said receiversand condensers and forming a part of the line circuits when the linesare closed.

12. In a telephone system, the combination of a substation and a centralstation and suitable line connection between the same, a central sourceof current supply connected with the lines, a two-way cord-circuit, acondenser in a strand of the cord-circuit, supervisory relays connectedwith one strand of the cord-circuit, supervisory lamps, local circuitsfor said lamps having normally closed switch-points controlled by saidrelays, a third relay having two coils connected between said source ofcurrent supply and the other strand of said cord circuit, said thirdrelay being arranged to control a normally open switch-point in thecircuits of said supervisory lamps, a trans mitter at one substationconnected and arranged to be supplied with current from said centralsource of current supply, a transmitter and local battery included in anormally open local circuit at the other substation, a receiver and acondenser in series and located at the substation having the localbattery, and an impedance coil arranged in parallel with said condenserand receiver and adapted to form part of the line circuit when the lineis closed.

13. In a telephone system, the combination of subscribers lines, a linerelay in each line, line lamp signals controlled by said line relays, acentral station, a central source of current supply connected with thelines and included in the local circuits of said line lamps, anoperators cord circuit, supervisory lamps associated with said cordcircuit, three supervisory relays for controlling normally closed andnormally open switch-points in the circuits of said supervisory lamps,condensers and receivers connected in series at the substation andimpedance coils arranged in parallel with said condensers and receiversand adapted to form part of the battery circuits when the lines areclosed, said condensers forming part of the talking circuits when thelines are closed, suitable means and connections whereby one supervisoryrelay in the 0perators cord circuit is energized over said local circuitcompleted when a cord con nection is established to line, and wherebyanother supervisory relay in such cord circuit is energized over theline circuit opened when the subscriber on the connected line hangs uphis telephone.

14. In a telephone system, a subscribers telephone equipment including acondenser having more than two terminals connected with said equipment,an operators cord circuit, two supervisory relays, a local circuit, acentral station, suitable means and conncctions whereby one supervisoryrelay in the operators cord circuit is energized over said local circuitcoi'npleted when a cord connection is established to line, and wherebythe other supervisory relay in such cord circuit is energized over theline circuit opened when the subscriber on the connected line hangs uphis receiving telephone.

1:"). In a telephone system, a condenser having more than two terminals,conductors leading from said terminals, an operators cord circuit, twosupervisory relays, a local circuit, a central station, suitable meansand connections whereby one supervisory relay in the operators cordcircuit is energized over said local circuit completed when acord-connection is established to line, and whereby the othersupervisory relay in such cord circuit is energized over the linecircuit opened when the subscriber on the connected line hangs up hisreceiving telephone, a re ceiver in which one conductor terminates, abell or ringer in which another conductor terminates, and an impedancecoil in which a third conductor terminates,

16. A telephone system comprising threeway condensers at thesubstations, line relays at the central station and supervisory relaysadapted to be placed in parallel with said line relays at the centralstation when connection is established between any two lines, anoperators cord circuit, a central station, suitable means andconnections whereby one supervisory relay in the operators cord circuitis energized over a local circuit completed when a cord-connection isestablished to line, and whereby the other supervisory relay in suchcord circuit is energized over the line circuit opened when thesubscriber on the connected line hangs up his receiving telephone.

17. In a telephone system, a telephone line, a line relay permanentlyconnected therewith, a supervisory relay in parallel with said linerelay, and a battery permanently connected with the line at a pointbetween said relays and feeding current through the same in parallel tothe line for talking purposes, said supervisory relay normally entirelydisconnected from said battery.

18. In a telephone system, a telephone line, a line relay permanentlyconnected therewith, a supervisory relay in parallel with said linerelay, and a battery having both poles permanently connected respectively with opposite sides of the line and feeding current through therelays in parallel to one side of the line for talking purposes, saidsupervisory relay normally enshunt for deenergizing the line relay ofsaid tirely disconnected from said battery. line to retire the linesignal thereof. 10 19. In a telephone system, a line, a di- Signed by meat Chicago, Cook county,

vided battery permanently connected there- Illinois, this 11th day ofFebruary, 1902.

with, a supervisory relay permanently con HENRY P. CLAUSEN.

nected with the middle point of said bat- W itnesses:

tery, a line relay and signal for said line, ARTHUR F. I)URANI),

and another supervisory relay forming a HARRY 1 .B.'\Ui\mixn'r1 1n1i.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. C.

